Interferon-γ drives macrophage reprogramming, cerebrovascular remodelling, and cognitive dysfunction in a zebrafish and a mouse model of ion imbalance and pressure overload

Aims: Dysregulated immune response contributes to inefficiency of treatment strategies to control hypertension and reduce the risk of end-organ damage. Uncovering the immune pathways driving the transition from the onset of hypertensive stimulus to the manifestation of multi-organ dysfunction are much-needed insights for immune targeted therapy.

Methods and results: To aid visualization of cellular events orchestrating multi-organ pathogenesis, we modelled hypertensive cardiovascular remodelling in zebrafish. Zebrafish larvae exposed to ion-poor environment exhibited rapid angiotensinogen up-regulation, followed by manifestation of arterial hypertension and cardiac remodelling that recapitulates key characteristics of incipient heart failure with preserved ejection fraction. In the brain, time-lapse imaging revealed the occurrence of cerebrovascular regression through endothelial retraction and migration in response to the ion-poor treatment. This phenomenon is associated with macrophage/microglia-endothelial contacts and endothelial junctional retraction. Cytokine and transcriptomic profiling identified systemic up-regulation of interferon-γ and interleukin 1β and revealed altered macrophage/microglia transcriptional programme characterized by suppression of innate immunity and vasculo/neuroprotective gene expression. Both zebrafish and a murine model of pressure overload-induced brain damage demonstrated that the brain pathology and macrophage/microglia phenotypic alteration are dependent on interferon-γ signalling. In zebrafish, interferon-γ receptor 1 mutation prevents cerebrovascular remodelling and dysregulation of macrophage/microglia transcriptomic profile. Supplementation of bone morphogenetic protein 5 identified from the transcriptomic approach as a down-regulated gene in ion-poor-treated macrophages/microglia that is rescued by interferon-γ blockage, mitigated cerebral microvessel loss. In mice subjected to transverse aortic constriction-induced pressure overload, typically developing cerebrovascular injury, neuroinflammation, and cognitive dysfunction, interferon-γ neutralization protected them from blood-brain barrier disruption, cerebrovascular rarefaction, and cognitive decline.

Conclusions: These findings uncover cellular and molecular players of an immune pathway communicating hypertensive stimulus to structural and functional remodelling of the brain and identify anti-interferon-γ treatment as a promising intervention strategy capable of preventing pressure overload-induced damage of the cerebrovascular and nervous systems.